Puncturing for structured low density parity check (LDPC) codes

Abstract

Certain aspects of the present disclosure generally relate to techniques for puncturing of structured low density parity check (LDPC) codes. A method for wireless communications by wireless node is provided. The method generally includes encoding a set of information bits based on a LDPC code to produce a code word, the LDPC code defined by a matrix having a first number of variable nodes and a second number of check nodes, puncturing the code word to produce a punctured code word, wherein the puncturing is performed according to a first puncturing pattern designed to puncture bits corresponding to one or more of the variable nodes having a certain degree of connectivity to the check nodes, and transmitting the punctured code word.

What is claimed is: 
     
       1. A method for wireless communications by a transmitting device, comprising:
 encoding, by encoder circuitry of the transmitting device, a set of information bits using a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 puncturing, by puncturing circuitry of the transmitting device, a plurality of bits at a start of the code word corresponding to at least the first variable node, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a punctured code word; and 
 transmitting, by transmitting circuitry of the transmitting device, the punctured code word in accordance with a radio technology across a wireless channel. 
 
     
     
       2. The method of  claim 1 , wherein puncturing the bits of the code word corresponding to at least the first variable node comprises puncturing the bits of the code word corresponding to the two variable nodes of the base graph having a highest degree of connectivity to the plurality of check nodes of the plurality of variable nodes. 
     
     
       3. The method of  claim 1 , wherein the at least one variable node comprises one or more variable nodes, of the plurality of variable nodes that, after puncturing, produces a punctured code word in which a fewest number of the plurality check nodes are connected to more than one variable node having punctured bits. 
     
     
       4. The method of  claim 1 , wherein the at least one variable node comprises one or more variable nodes, of the plurality of variable nodes that, after puncturing, produces a punctured code word in which a fewest number of closed loops. 
     
     
       5. The method of  claim 1 , wherein the encoding using the LDPC code results in a code rate of 5/6 for the code word and the puncturing results in a code rate of 7/8 for the punctured code word. 
     
     
       6. The method of  claim 1 , further comprising, for a retransmission of the set of information bits, puncturing different bits of the code word. 
     
     
       7. The method of  claim 6 , wherein the different bits correspond to one or more different variable nodes with a same degree of connectivity to check nodes as the at least one variable node. 
     
     
       8. The method of  claim 6 , wherein puncturing the different bits comprises puncturing bits in the code word at a defined offset relative to the punctured bits in the punctured code word. 
     
     
       9. The method of  claim 1 , wherein the LDPC code comprises an 802.11 Wi-Fi LDPC code. 
     
     
       10. The method of  claim 1 , further comprising puncturing bits of the code word, after the bits corresponding to the at least one variable node, at a periodicity. 
     
     
       11. The method of  claim 1 , further comprising puncturing bits from an end of the code word. 
     
     
       12. The method of  claim 11 , wherein puncturing bits from the end of the code word comprises puncturing the bits at a periodicity. 
     
     
       13. The method of  claim 1 , wherein:
 the code word comprises a stream of LDPC encoded bits; and 
 puncturing the plurality of bits at the start of the code word comprises puncturing the plurality of bits from a starting bit of the stream of LDPC encoded bits. 
 
     
     
       14. An apparatus for wireless communications by a transmitting device, comprising:
 encoding circuitry configured to encode a set of information bits using a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 puncturing circuitry configured to puncture a plurality of bits at a start of the code word corresponding to at least the first variable node, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a punctured code word; and 
 transmitting circuitry configured to transmit the punctured code word in accordance with a radio technology across a wireless channel. 
 
     
     
       15. The apparatus of  claim 14 , wherein the puncturing circuitry configured to puncture the bits of the code word corresponding to at least the first variable node comprises puncturing circuitry configured to puncture the bits of the code word corresponding to the two variable nodes of the base graph having a highest degree of connectivity to the plurality of check nodes of the plurality of variable nodes. 
     
     
       16. The apparatus of  claim 14 , wherein the at least one variable node comprises one or more variable nodes, of the plurality of variable nodes that, after puncturing, produces a punctured code word in which a fewest number of the plurality check nodes are connected to more than one variable node having punctured bits. 
     
     
       17. The apparatus of  claim 14 , wherein the at least one variable node comprises one or more variable nodes, of the plurality of variable nodes that, after puncturing, produces a punctured code word in which a fewest number of closed loops. 
     
     
       18. The apparatus of  claim 14 , wherein the encoding using the LDPC code results in a code rate of 5/6 for the code word and the puncturing results in a code rate of 7/8 for the punctured code word. 
     
     
       19. The apparatus of  claim 14 , wherein the puncturing circuitry is further configured to, for a retransmission of the set of information bits, puncture different bits of the code word. 
     
     
       20. The apparatus of  claim 19 , wherein the different bits correspond to one or more different variable nodes with a same degree of connectivity to check nodes as the at least one variable node. 
     
     
       21. The apparatus of  claim 19 , wherein puncturing the different bits comprises puncturing bits in the code word at a defined offset relative to the punctured bits in the punctured code word. 
     
     
       22. The apparatus of  claim 14 , wherein the LDPC code comprises an 802.11 Wi-Fi LDPC code. 
     
     
       23. The apparatus of  claim 14 , wherein the puncturing circuitry is further configured to puncture bits of the code word, after the bits corresponding to the at least one variable node, at a periodicity. 
     
     
       24. The apparatus of  claim 14 , wherein the puncturing circuitry is further configured to puncture bits from an end of the code word. 
     
     
       25. The apparatus of  claim 24 , wherein the puncturing circuitry configured to puncture bits from the end of the code word comprises puncturing circuitry configured to puncture the bits from the end of the code word at a periodicity. 
     
     
       26. An apparatus for wireless communication by a transmitting device, comprising:
 means for encoding, by the transmitting device, a set of information bits using a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 code for puncturing, by the transmitting device, a plurality of bits at a start of the code word corresponding to at least the first variable node, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a punctured code word; and 
 code for transmitting, by the transmitting device, the punctured code word in accordance with a radio technology across a wireless channel. 
 
     
     
       27. A non-transitory computer readable medium storing computer executable code thereon for wireless communications by a transmitting device, comprising:
 code for encoding, by encoding circuitry of the transmitting device, a set of information bits using a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 code for puncturing, by puncturing circuitry of the transmitting device, a plurality of bits at a start of the code word corresponding to at least the first variable node, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a punctured code word; and 
 code for transmitting, by transmitting circuitry of the transmitting device, the punctured code word in accordance with a radio technology across a wireless channel. 
 
     
     
       28. A method for wireless communications by a transmitting device, comprising:
 encoding, by encoder circuitry of the transmitting device, a set of information bits using a low density parity check (LDPC) code to produce a first code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 puncturing, by puncturing circuitry of the transmitting device, a plurality of bits at a start of the first code word corresponding to at least two first variable nodes, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a first punctured code word; 
 transmitting, by transmitting circuitry of the transmitting device, a signal based on the first punctured code word in accordance with a radio technology across a wireless channel; 
 re-encoding, by the encoder circuitry of the transmitting device, the set of information bits using the LDPC code to produce a second code word; 
 puncturing, by the puncturing circuitry of the transmitting device, a different plurality of bits of the second code word than the plurality of bits at the start of the first code word to produce a second punctured code word; and 
 transmitting, by the transmitting circuitry of the transmitting device, a signal based on the second punctured code in accordance with the radio technology across the wireless channel. 
 
     
     
       29. The method of  claim 28 , wherein the different bits correspond to one or more different variable nodes with a same degree of connectivity to the plurality of check nodes as the at least two variable nodes. 
     
     
       30. The method of  claim 28 , wherein puncturing the different bits comprises puncturing bits in the code word at a defined offset relative to the punctured bits in the first punctured code word. 
     
     
       31. The method of  claim 28 , wherein puncturing the different bits comprises puncturing bits of the second code word, after the plurality of bits at the start of the code word, at a periodicity. 
     
     
       32. A method for wireless communications by a transmitting device, comprising:
 encoding, by encoder circuitry of the transmitting device, a set of information bits using a low density parity check (LDPC) code to produce a first code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 puncturing, by puncturing circuitry of the transmitting device, a first set of bits corresponding to one or more variable nodes, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a first punctured code word; 
 transmitting, by transmitting circuitry of the transmitting device, a first signal based on the first punctured code word in accordance with a radio technology across a wireless channel; 
 encoding, by the encoder circuitry of the transmitting device, the set of information bits using the LDPC code to produce a second code word; 
 puncturing, by the puncturing circuitry of the transmitting device, a second set of bits of the second code word at a positive offset relative to the first set of bit in the first punctured code word to produce a second punctured code word; and 
 transmitting, by the transmitting circuitry of the transmitting device, a second signal based on the second punctured code in accordance with the radio technology across the wireless channel. 
 
     
     
       33. The method of  claim 32 , wherein the first set of bits corresponding to the one or more variable nodes comprise a plurality of bits at a start of the code word. 
     
     
       34. The method of  claim 32 , wherein the first set of bits corresponding to the one or more variable nodes comprises a plurality of bits corresponding to at least two variable nodes having the highest degree of connectivity to the plurality of check nodes. 
     
     
       35. The method of  claim 32 , further comprising puncturing bits from an end of the code word. 
     
     
       36. An apparatus for wireless communications by a transmitting device, comprising:
 encoding circuitry configured to encode a set of information bits using a low density parity check (LDPC) code to produce a first code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 puncturing circuitry configured to puncture a first set of bits corresponding to one or more variable nodes, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a first punctured code word; and 
 transmitting circuitry configured to transmit a first signal based on the first punctured code word in accordance with a radio technology across a wireless channel, wherein:
 the encoding circuitry is configured to encode the set of information bits using the LDPC code to produce a second code word; 
 the puncturing circuitry is configured to puncture a second set of bits of the second code word at a positive offset relative to the first set of bit in the first punctured code word to produce a second punctured code word; and 
 the transmitting circuitry configured to transmit a second signal based on the second punctured code in accordance with the radio technology across the wireless channel. 
 
 
     
     
       37. The apparatus of  claim 36 , wherein the first set of bits corresponding to the one or more variable nodes comprise a plurality of bits at a start of the code word. 
     
     
       38. The apparatus of  claim 36 , wherein the first set of bits corresponding to the one or more variable nodes comprises a plurality of bits corresponding to at least two variable nodes having the highest degree of connectivity to the plurality of check nodes. 
     
     
       39. The apparatus of  claim 36 , further comprising puncturing bits from an end of the code word. 
     
     
       40. A method for wirelessly transmitting data in accordance with a radio technology, comprising:
 encoding, by encoder circuity, a set of information bits based on a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes; 
 puncturing, by puncturing circuitry, a first set of bits of the code word corresponding to a variable node of the first number of variable nodes having a highest degree of connectivity to the second number of check nodes and one or more bits at the end of the code word to produce a first punctured code word; 
 transmitting, via transmitting circuitry, the first punctured code word in accordance with the radio technology across a wireless channel; 
 puncturing, by puncturing circuitry, at least a second set of bits of the code word that are at a positive offset relative to the bits in the first punctured code word to produce a second punctured code word; and, 
 transmitting, via transmitting circuitry, the second punctured code word in accordance with the radio technology across a wireless channel. 
 
     
     
       41. An apparatus for wirelessly transmitting data in accordance with a radio technology, comprising:
 encoding circuitry configured to encode a set of information bits based on a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes; 
 puncturing circuitry configured to puncture a first set of bits of the code word corresponding to a variable node of the first number of variable nodes having a highest degree of connectivity to the second number of check nodes and one or more bits at the end of the code word to produce a first punctured code word; and 
 transmitting circuitry configured to transmit the first punctured code word in accordance with the radio technology across a wireless channel, wherein:
 the puncturing circuitry is configured to puncture at least a second set of bits of the code word that are at a positive offset relative to the bits in the first punctured code word to produce a second punctured code word; and 
 the transmitting circuitry is configured to transmit the second punctured code word in accordance with the radio technology across a wireless channel. 
 
 
     
     
       42. A method for wireless communications by a transmitting device, comprising:
 encoding, by encoder circuitry of the transmitting device, a set of information bits using a low density parity check (LDPC) code to produce a first code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 puncturing, by puncturing circuitry of the transmitting device, a first set of bits corresponding to one or more variable nodes, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a first punctured code word; 
 puncturing, by the puncturing circuitry of the transmitting device, a second set of bits of the first punctured code word at a positive offset relative to the first set of bits in the first punctured code word to produce a second punctured code word; and 
 transmitting, by the transmitting circuitry of the transmitting device, a signal based on the second punctured code. 
 
     
     
       43. A wireless communication device configured to communicate wireless signals, the device comprising:
 encoder circuitry configured to encode information bits using a low density parity check (LDPC) code to produce a first code word, the LDPC code defined by a base graph having a plurality of variable nodes and a plurality of check nodes; 
 puncturing circuitry configured to puncture a first set of bits corresponding to one or more variable nodes, having a highest degree of connectivity to the plurality of check nodes, of the plurality of variable nodes of the base graph to produce a first punctured code word; 
 said puncturing circuitry configured to puncture a second set of bits of the first punctured code word at a positive offset relative to the first set of bits in the first punctured code word to produce a second punctured code word; and 
 transmitting circuitry configured to transmit wireless signaling based on the second punctured code word. 
 
     
     
       44. A method for wirelessly communicating data in accordance with a radio technology, comprising:
 encoder circuity configured to encode a set of information bits based on a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes; 
 puncturing circuitry configured to puncture bits of the code word corresponding to at least the variable node of the first number of variable nodes at a start of the code word having a highest degree of connectivity to the second number of check nodes to produce a punctured code word; 
 puncturing circuitry configured to puncture one or more bits at an end of the punctured code word starting at a first end bit to produce a first punctured code word; 
 transmitting circuitry configured to transmit wireless signaling associated with the first punctured code word; 
 puncturing circuitry configured to puncture one or more bits at a start of the punctured code word and one or more bits at an end of the punctured code word, starting at a second end bit, to produce a second punctured code word, where the second end bit is a positive offset from the first end bit; and 
 transmitting circuitry configured to transmit wireless signaling associated with the second punctured code word. 
 
     
     
       45. A method for wirelessly transmitting data in accordance with a radio technology, comprising:
 encoding, by encoder circuity, a set of information bits based on a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes; 
 puncturing, by puncturing circuitry, bits of the code word corresponding to at least the variable node of the first number of variable nodes at a start of the code word having a highest degree of connectivity to the second number of check nodes to produce a punctured code word; 
 puncturing, by puncturing circuitry, one or more bits at an end of the punctured code word starting at a first end bit to produce a first punctured code word; 
 transmitting, via transmitting circuitry, signaling associated with the first punctured code word in accordance with the radio technology across a wireless channel; 
 puncturing, by puncturing circuitry, one or more bits a start of the punctured code word and one or more bits at an end of the punctured code word, starting at a second end bit, to produce a second punctured code word, where the second end bit is a positive offset from the first end bit; and, 
 transmitting, via transmitting circuitry, signaling associated with the second punctured code word in accordance with the radio technology across a wireless channel. 
 
     
     
       46. In a communication system comprising multiple wireless communication devices configured to communication wireless radio signals with one or more other wireless communication devices, a wireless communication node comprising:
 encoder circuity configured to encode a set of information bits based on a low density parity check (LDPC) code to produce a code word, the LDPC code defined by a base graph having a first number of variable nodes and a second number of check nodes; 
 puncturing circuitry configured to: (i) puncture bits of the code word corresponding to at least the variable node of the first number of variable nodes at a start of the code word having a highest degree of connectivity to the second number of check nodes to produce a punctured code word; (ii) puncture one or more bits at an end of the punctured code word starting at a first end bit to produce a first punctured code word; (iii) puncture one or more bits at a start of the punctured code word and one or more bits at an end of the punctured code word, starting at a second end bit, to produce a second punctured code word, the second end bit spaced apart from the first end bit; and 
 transmitting circuitry configured to transmit at least one of signaling associated with the first punctured code word or signaling associated with the second punctured code word.